Lightweight knuckle with in-cast spindle

ABSTRACT

An independent vehicle suspension includes a knuckle assembly supported by control arms or links. The knuckle assembly includes a forged, elongated steel spindle, one end of which includes a pair of axially-spaced radial flanges separated by a radially-enlarged shank portion. The knuckle assembly further includes an aluminum knuckle body defining at least one attachment point for the links. The knuckle assembly is formed by insert-casting the knuckle body about the shank portion of the spindle to thereby fully encapsulate the shank portion within, and at least partially encircle an axial portion of each spindle flange with, the as-cast knuckle body. A radial shoulder, for example, machined on the spindle&#39;s outboard end proximate to the outboard flange, axially supports the inner race of a bearing assembly, thereby advantageously reducing wheelend run-out. One or more peripheral flats on either spindle flange resists torsion, thereby allowing the machining of spindle surfaces after insert-casting.

FIELD OF INVENTION

[0001] The invention relates to an automotive suspension knuckleassembly for supporting a wheelend assembly.

BACKGROUND OF THE INVENTION

[0002] The prior art teaches knuckle assemblies for use in automotivesuspensions in which a cast, stamped, or forged knuckle body is providedwith a toleranced bore within which to receive a precisely-machinedinboard end of an elongated cast or forged spindle. The spindle isinserted within the bore of the knuckle body and thereafter typicallymaintained in the knuckle body by virtue of a press or shrink(interference) fit achieved between the bore and the machined end of thespindle.

[0003] Unfortunately, this prior art approach requires the machining ofboth the knuckle body bore and the inboard end of the spindle to ratherhigh tolerances, thereby increasing manufacturing costs. Moreover, theresulting interference between the installed spindle and the knucklebody is further characterized by a relatively limited ability to resistthe application of an applied torque, as might be experienced if theoutboard (cantilevered) end of the spindle was machined after thespindle is installed in the knuckle body. As a result, the prior artpress-fit and shrink-fit approaches necessarily require that theoutboard end of the spindle also be machined to a desired surfacecontour and dimensional tolerance before the spindle is installed in theknuckle body.

SUMMARY OF THE INVENTION

[0004] In accordance with the invention, a knuckle assembly for avehicle suspension adapted to support a bearing race of a wheelendassembly includes an elongated spindle formed, for example, of a cast orforged steel that is mechanically captured within a cast knuckle body.The spindle, which is conveniently made of a cast or forged steel,includes an inboard end having a first radial flange and a shank portionproximate to the first flange. The knuckle body is insert-cast about theshank portion of the spindle such that the as-cast knuckle body iscontiguous with a first face of the first flange and the shank portion,whereby a mechanical interlock is achieved between the spindle andknuckle body.

[0005] The spindle further includes an outboard having a radial shoulderthat defines both a planar first surface adapted to axially support thebearing race of the wheelend assembly, and a cylindrical second surfaceadapted to radially support the bearing race. Preferably, where theknuckle body is cast of aluminum, the radial shoulder is axially spacedfrom the shank portion of the spindle such that the typically steelbearing race is maintained at least a minimum distance from the as-castaluminum knuckle body, whereby galvanic action between the bearing raceand the knuckle body is advantageously avoided.

[0006] In a preferred embodiment, an axial face and at least a portionof a peripheral surface of the first flange is captured within theas-cast knuckle body to provide an improved mechanical interlock.Further, the peripheral surface of the first flange preferably includesa peripheral flat or other noncylindrical characteristic, such that thespindle is able to resist relative torsional movement of the spindlewithin the as-cast knuckle body. In this manner, the inventionadvantageously provides a mechanical interlock is achieved between theperipheral surface of the spindle and the as-cast knuckle body thatfeatures improved resistance to a relative rotation of the spindlewithin the as-cast knuckle body.

[0007] In accordance with another aspect of the invention, in apreferred embodiment, the inboard end of the spindle includes a secondradial flange that is axially-spaced from the first flange and isproximate to the shank portion of the spindle, and the knuckle body iscast such that the as-cast knuckle body is contiguous with a respective,opposed face of each flange to thereby achieve an improved axialinterlock between the spindle and the as-cast knuckle body. When thespindle is provided with such a second flange, it will be appreciatedthat the radial shoulder of the outboard end of the spindle isadvantageously defined by the second face of the second flange as itprojects from the as-cast knuckle body.

[0008] In accordance with yet another feature of the invention, thefirst spindle surface adapted to axially support the bearing race of thewheelend assembly has a first dimensional tolerance, while the shankportion of the spindle has a second dimensional tolerance substantiallylower than the first dimensional tolerance. By way of example, theinvention advantageously lowers manufacturing costs by using an as-castor as-forged surface finish on the captured shank portion of thespindle, thereby requiring a precisely-machined finish only on theoutboard end of the spindle that supports the bearing race.

[0009] Under the invention, a method is also provided for making aknuckle assembly for a vehicle suspension that includes the steps ofinserting a first end of an elongated spindle into a molding cavity of acasting mold such that a first radial flange and an adjacent shankportion of the spindle are disposed within the molding cavity, while asecond end of the spindle extends through the casting mold away from themold cavity. The method also includes insert-casting a knuckle bodywithin the molding cavity such that the as-cast knuckle body iscontiguous with the shank portion, a first face of the first flange, andat least a portion of a peripheral surface of the first flange. Themethod further includes machining the second end of the spindle tothereby provide a finished radial shoulder on the second end of thespindle, with the shoulder defining a first surface adapted to axiallysupport the bearing race of the wheelend assembly and a finishedcylindrical surface adapted to radially support the bearing race of thewheelend assembly.

[0010] In a preferred method wherein the spindle includes a secondradial flange axially-spaced from the first flange and adjacent to theshank portion, the inserting step places a first face of the secondflange and at least a portion of a peripheral surface of the secondflange within the molding cavity. A preferred method further includesforming a peripheral flat or other noncylindrical characteristic on theperipheral surface of at least one flange, whereby the spindle ismechanically rotationally locked within the knuckle body to therebyresist the application of a torque.

[0011] Because the spindle is mechanically rotationally locked withinthe as-cast knuckle body, the invention advantageously may furtherinclude machining the bearing-supporting first surface of the spindlesubsequent to insert-casting, thereby improving the relative alignmentof the spindle/radial shoulder with a plurality of attachment pointsthat are themselves defined on the as-cast knuckle body. Alternatively,the invention contemplates machining the bearing-supporting surfaces onthe outboard end of the spindle before the spindle is insert-cast intothe knuckle body, whereupon certain features of the knuckle body maythereafter be machined with reference to the pre-established spindlesurfaces. By way of example, under the alternative approach, suitablebores in the knuckle body for use with the links and defining a brakecaliper mount are easily machined after with respect to the in-castspindle to achieve close tolerances with respect to the spindle axis.

[0012] In accordance with yet another aspect of the invention, thefinished shoulder on the spindle is machined to a higher dimensionaltolerance than the shank portion to thereby advantageously reducewheelend assembly run-out. Indeed, under the invention, the shankportion is preferably maintained in an as-cast or as-forged surfacefinish, thereby advantageously reducing the amount of machining thatmust be performed on the spindle.

[0013] Additional benefits and advantages of the invention will becomeapparent to those skilled in the art to which the present inventionrelates from the subsequent description of the preferred embodiment andthe appended claims, taken in conjunction with the accompanyingdrawings.

BRIEF DESCRIPTION OF THE DRAWINGS

[0014]FIG. 1 is a side elevation of an exemplary first knuckle assemblyfor an independent vehicle suspension in accordance with the invention,also showing in partial axial section a supported wheelend assembly;

[0015]FIG. 2 is a front elevation of the first knuckle assembly of FIG.1;

[0016]FIG. 3 is a sectional view of the first knuckle assembly, takenalong line 3-3 of FIG. 2;

[0017]FIG. 4 is an end view of the spindle before the spindle is in-castwithin the knuckle body of the first knuckle assembly;

[0018]FIG. 5 is a sectional view of an exemplary second knuckle assemblyincorporating a spindle having an alternative shank configuration; and

[0019]FIG. 6 is a partially diagrammatic view of a method in accordancewith the invention for making a knuckle assembly for a vehiclesuspension.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT

[0020] Referring to FIGS. 1-4, an exemplary first knuckle assembly 10for a vehicle suspension adapted to support a bearing race 12 of awheelend assembly 14 includes an elongated spindle 16 that ismechanically captured within a cast knuckle body 18. As best seen inFIG. 3, the spindle 16, which is conveniently cast or forged from anysuitable material such as a nodular iron or steel, includes a first,“inboard” end 20 and a second, “outboard” end 22. The inboard end 20 ofthe spindle 16 is provided with a pair of axially-spaced radial flanges24, 26, separated by a generally-right-cylindrical shank portion 28.

[0021] As illustrated in partial section in FIG. 3, the knuckle body 18is insert-cast about the shank portion 28 of the spindle 16 such thatthe as-cast knuckle body 18 is contiguous with each of a first face 30of the inboard flange 24, an opposed first face 32 of the outboardflange 26, and the shank portion 28, whereby a mechanical interlock isachieved between the spindle 16 and as-cast knuckle body 18. And, asseen in FIG. 3, to ensure the contiguity of the as-cast knuckle bodywith the opposed faces 30,32 of the flanges 24,26, the knuckle body 18is preferably cast so as to be contiguous with at least a portion of arespective peripheral surface 34,36 of each flange 24,26.

[0022] While the knuckle body 18 is cast of any suitable material, toadvantageously provide the first knuckle assembly 10 with a reducedweight and, hence, provide the vehicle incorporating the first knuckleassembly 10 with a reduced unsprung wheelend mass, the knuckle body 18is formed of a cast aluminum alloy, such as A356. It will be appreciatedthat the invention contemplates use of lightweight cast materials inplace of aluminum.

[0023] As best seen in FIGS. 1 and 3, the outboard end 22 of the spindle16 further includes a radial shoulder 38 that defines a planar andannular first surface 40 adapted to axially support the inboard innerbearing race 12 of the wheelend assembly 14, and a cylindrical secondsurface 42 adapted to radially support the inboard and outboard innerbearing races 12, 44. The first surface 40 is machined to a relativelyhigh tolerance to thereby advantageously reduce wheelend assemblyrun-out. To avoid galvanic action between the typically-steel inboardinner bearing race 12 and the aluminum knuckle body 18, the radialshoulder 38 is axially spaced from the shank portion 28 of the spindle16 such that the inboard inner bearing race 12 is maintained at least aminimum distance from the adjacent outboard surface 46 of the as-castaluminum knuckle body 18. In the first knuckle assembly 10, the radialshoulder 38 is conveniently defined by the outboard annular face of thespindle's outboard flange 26.

[0024] In accordance with an aspect of the invention, the first surface40 on the outboard end 22 of the spindle 16, adapted to axially supportthe bearing race 12, is machined to a higher dimensional tolerance thanthe shank portion 28. Indeed, under the invention, the shank portion 28is conveniently maintained in an as-cast or as-forged surface finish, ornearly so, thereby advantageously reducing the amount of machining thatmust be performed on the spindle 16. In this regard, it is noted that anas-forged surface is likely preferably over an as-cast surface, in partdue to its relatively lesser surface porosity.

[0025] In accordance with another aspect of the invention, and asillustrated in FIG. 4, the peripheral surface 34 of the spindle'sinboard flange 24 includes a plurality of flats 50 that provide theperipheral surface 34 with a noncylindrical characteristic. Because theknuckle body 18 is cast in contiguity with at least a portion of theseperipheral surface flats 50, a mechanical interlock is achieved betweenthe peripheral surface flats 50 of the spindle 16 and the as-castknuckle body 18 that features improved resistance to a relative rotationof the spindle 16 within the as-cast knuckle body 18. FIG. 4 also showsan axial bore 52 formed in the inboard end of the spindle 16, whichadvantageously serves to further reduce the overall weight of the firstknuckle assembly 10.

[0026] An exemplary second knuckle assembly 54 is illustrated in partialcross-section in FIG. 5. The second knuckle assembly 54 similarlyincludes an elongated spindle 56 whose inboard end 58 is captured in acast knuckle body 60. As in the first knuckle assembly 10, the secondknuckle assembly's spindle 56 includes an inboard flange 62 and anoutboard flange 64, separated by a “cylindrical” shank portion 66 havingthe shape of a conical frustum. As in the first knuckle assembly 10, theannular first surface 68 that axially supports the inner race of thebearing assembly (not shown) is conveniently defined on the spindle'soutboard flange 64, opposite the frustoconical “face” of the flange 26defined by the spindle's shank portion 66.

[0027]FIG. 6 illustrates the insert-casting of the knuckle body 18 ofthe first knuckle assembly 10 about the “as-forged” inboard end 20 ofthe spindle 16. Specifically, the inboard end 20 of the spindle 16 isinserted into a molding cavity 70 of a casting mold 72 such that theinboard flange 24, the shank portion 28, and a portion of the outboardflange 26 are each disposed within the molding cavity 70, while theoutboard end 22 of the spindle 16 extends through the casting mold 72away from the mold cavity 70. The aluminum knuckle body material 74 isthen directed into the molding cavity 70 such that the as-cast knucklebody 18 is contiguous with the inboard flange's peripheral surface 34and adjacent face 30, the shank portion 28, the outboard flange'sadjacent face 32, and a portion of the outboard flange's peripheralsurface 36.

[0028] After the as-cast knuckle body 18 is removed from the castingmold 72, the knuckle body 18 is fixtured and the spindle's outboard end22 is machined to a desired dimensional tolerance and surface finish tothe spindle's bearing-supporting first and second surfaces 40, 42. Itwill be appreciated that the robust mechanical interlock achievedbetween the spindle 16 and the as-cast knuckle body 18 advantageouslypermits the post-casting machining of the outboard end 22 of the spindle16, thereby improving the relative alignment of the spindle'sbearing-supporting surfaces 40, 42 with a plurality of attachment points76 that are themselves defined on the as-cast knuckle body 18 (as seenin FIG. 1).

[0029] It will be appreciated, however, that the invention contemplatesmachining the outboard end 22 of the spindle 16 prior to insert-casting,where desired, for example, to otherwise define the peripheral surfaceflats 50 or other noncylindrical peripheral characteristic on theinboard flange 24. As noted above, under the invention, the shankportion 28 of the spindle 16 is preferably maintained in an as-cast oras-forged surface finish, thereby advantageously reducing the amount ofmachining that must be performed on the spindle 16.

[0030] While the above description constitute the preferred embodiments,it will be appreciated that the invention is susceptible tomodification, variation and change without departing from the properscope and fair meaning of the subjoined claims.

I claim:
 1. A knuckle assembly for a vehicle suspension adapted tosupport a bearing race of a wheelend assembly, the knuckle assemblycomprising: an elongated spindle having an outboard end and an inboardend, wherein the inboard end includes a first radial flange and a shankportion proximate to the first flange, and wherein the outboard endincludes a radial shoulder defining a planar first surface adapted toaxially support the bearing race of the wheelend assembly, and acylindrical second surface adapted to radially support the bearing raceof the wheelend assembly; and a knuckle body insert-cast about the shankportion of the spindle, wherein the as-cast knuckle body is contiguouswith a first face of the first flange and the shank portion.
 2. Theknuckle assembly of claim 1, wherein the shank portion is cylindrical.3. The knuckle assembly of claim 2, wherein the shank portion is of agenerally-right-cylindrical configuration and is concentric about thelongitudinal axis of the spindle.
 4. The knuckle assembly of claim 1,wherein the spindle includes a second radial flange proximate to theshank portion of the spindle and axially spaced from the first flange.5. The knuckle assembly of claim 4, wherein a first face of the secondflange is in axial opposition with the first face of the first flange;and wherein the as-cast knuckle body is contiguous with the first faceof the second flange.
 6. The knuckle assembly of claim 4, wherein theas-cast knuckle body defines a knuckle body surface proximate to thesecond flange of the spindle, and wherein the second flange has a secondface opposite to the first face, the second face of the second flangebeing axially spaced from the knuckle body surface.
 7. The knuckleassembly of claim 6, wherein the first surface of the outboard end ofthe spindle is defined by the second face of the second flange.
 8. Theknuckle assembly of claim 4, wherein one of the first and second flangeshas a peripheral surface, and wherein the as-cast knuckle body iscontiguous with at least a portion of the peripheral surface of the oneflange.
 9. The knuckle assembly of claim 8, wherein the peripheralsurface of the one flange includes a peripheral flat, and wherein theas-cast knuckle body is contiguous with at least a portion of theperipheral flat, whereby a mechanical interlock is achieved between theperipheral surface of the spindle and the as-cast knuckle body to resistrelative rotation of the spindle within the as-cast knuckle body
 10. Theknuckle assembly of claim 8, wherein the peripheral surface of the oneflange is noncylindrical, whereby the one flange resists relativerotation of the spindle within the as-cast knuckle body.
 11. The knuckleassembly of claim 1, wherein the first surface of the spindle adapted toaxially support the bearing race of the wheelend assembly has a firstdimensional tolerance, and wherein the shank portion of the spindle hasa second dimensional tolerance substantially lower than the firstdimensional tolerance.
 12. The knuckle assembly of claim 11, wherein thefirst surface of the spindle is finished in a machining operation. 13.The knuckle assembly of claim 10, wherein the spindle is a casting, andwherein the shank portion of the spindle is a substantially as-castsurface.
 14. The knuckle assembly of claim 10, wherein the spindle is acasting, and wherein the shank portion of the spindle is a substantiallyas-forged surface.
 15. A method for making a knuckle assembly for anindependent vehicle suspension adapted to support a bearing race of awheelend assembly, the method comprising: inserting an elongated spindleinto a molding cavity of a casting mold such that a first radial flangeon the spindle proximate to a first end of the spindle and a shankportion of the spindle adjacent to the first flange are disposed withinthe molding cavity, whereby a second end of the spindle extends throughthe casting mold away from the mold cavity; insert-casting a knucklebody within the molding cavity such that the as-cast knuckle body iscontiguous with the shank portion, a first face of the first flange, andat least a portion of a peripheral surface of the first flange; andmachining the second end of the spindle to thereby provide a finishedradial shoulder on the second end of the spindle, the shoulder defininga first surface adapted to axially support the bearing race of thewheelend assembly and a finished cylindrical surface adapted to radiallysupport the bearing race of the wheelend assembly.
 16. The method ofclaim 15, wherein the spindle includes a second radial flangeaxially-spaced from the first flange and adjacent to the shank portion,and wherein inserting places a first face of the second flange and atleast a portion of a peripheral surface of the second flange within themolding cavity.
 17. The method of claim 15, including forming aperipheral flat on the peripheral surface of the first flange.
 18. Themethod of claim 15, wherein machining the radial shoulder of the spindleis performed subsequent to insert-casting.
 19. The method of claim 15,wherein the finished shoulder is machined to a higher dimensionaltolerance than the shank portion.